Dr. Christie’s research focuses on the fundamental aspects of neurotransmission at synapses, the point-to-point connections between neurons. In particular, his research group studies how the strength of synaptic transmission becomes stronger or weaker due to preceding neuronal activity. The remarkable ability of synapses to alter their response properties in an activity-dependent manner is an integral component of neuronal function. This plasticity, or malleability, of synaptically connected neurons affects behavior and allows the brain to respond, adapt and learn from its experiences. Long-term alterations in the transmission properties of synapses provide a basis for learning and memory whereas short-term alterations are necessary to rapidly organize information in neuronal circuits. Building from a basic understanding of plasticity at single synapses, Dr. Christie would ultimately like to understand how changes in synaptic strength are integrated within small populations of connected neurons (microcircuits) to generate physiologically relevant computations.
To address these questions, it is necessary to directly record the activity of synapses in brain tissue. Dr. Christie utilizes patch-clamp electrophysiology to study electrical responses in neurons generated from the opening of neurotransmitter-gated ion channels located at a synapse. Recordings are made from acute brain slice preparations, including cerebellum, hippocampus, cortex, and olfactory bulb. In conjunction with electrophysiological measurements, he also uses two-photon laser scanning microscopy to directly view fluorescently labeled cells as well as image the passage of ions, such as calcium, through pre- and postsynaptic channels. In this way, single synapses can be studied in isolation or as an ensemble of all active synapses in a single cell.